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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#if defined(__linux__)
#include <semaphore.h>
#endif
#include <queue>
#include "mongo/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/platform/mutex.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/util/concurrency/admission_context.h"
#include "mongo/util/concurrency/mutex.h"
#include "mongo/util/concurrency/ticketholder.h"
#include "mongo/util/hierarchical_acquisition.h"
#include "mongo/util/time_support.h"
namespace mongo {
class SemaphoreTicketHolder final : public TicketHolder {
public:
explicit SemaphoreTicketHolder(int numTickets, ServiceContext* serviceContext);
~SemaphoreTicketHolder() override final;
int32_t available() const override final;
int64_t queued() const override final {
auto removed = _semaphoreStats.totalRemovedQueue.loadRelaxed();
auto added = _semaphoreStats.totalAddedQueue.loadRelaxed();
return std::max(added - removed, (int64_t)0);
};
int64_t numFinishedProcessing() const override final;
private:
boost::optional<Ticket> _waitForTicketUntilImpl(OperationContext* opCtx,
AdmissionContext* admCtx,
Date_t until) override final;
boost::optional<Ticket> _tryAcquireImpl(AdmissionContext* admCtx) override final;
void _releaseToTicketPoolImpl(AdmissionContext* admCtx) noexcept override final;
void _appendImplStats(BSONObjBuilder& b) const override final;
void _resize(int32_t newSize, int32_t oldSize) noexcept override final;
QueueStats& _getQueueStatsToUse(const AdmissionContext* admCtx) noexcept override final {
return _semaphoreStats;
}
#if defined(__linux__)
mutable sem_t _sem;
#else
bool _tryAcquire();
int32_t _numTickets;
Mutex _mutex =
MONGO_MAKE_LATCH(HierarchicalAcquisitionLevel(0), "SemaphoreTicketHolder::_mutex");
stdx::condition_variable _newTicket;
#endif
QueueStats _semaphoreStats;
};
} // namespace mongo
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